Stone- Based on the instructions Mr. Rusty posted, it doesn't look like redevelopment is needed. Negative intensification can be done with lights on.
Do you have negatives which could use some intensification? If so, I wouldn't rely on the old copper you have. When I've needed a slight boost, I've used selenium at about 1:4. I think Photographer's Formulary sells a chromium intensifier, too.
Bleach/redevelopment in sepia probably gives the most increase.